The Holographic Microwave Imaging system is an active microwave imaging based on radar technique. Previous works have investigated its capability to detect tumors from early breast cancer. The results demonstrate a proper image reconstruction with different algorithms focused on near-field and far-field conditions. The system used for far-field scenery uses a random spatial distribution for antennas array. In this paper, experimental studies are done to validate the benefits of the random positions array and the non-viability of the uniform ones. Results show the accuracy for detection of multiple tumors in a breast phantom with a random spatial distribution. The sphere tumor samples of 0.7 cm and 1 cm diameter are successfully located and coins as conductor references validate the distance and area of the targets imaged. On the other hand, the experiments with a uniform distributed antennas array exhibit the presence of replicas in the image, showing the inefficiency of this set-up.